Proposal to Eliminate Urethane-Treated Positive Control Dose Groups in 26-Week Tg.rasH2 Carcinogenicity Studies.

Short-term (26 weeks) Tg.rasH2 mouse carcinogenicity studies have been conducted as an alternative model to the conventional 2-year mouse carcinogenicity studies, using urethane as a positive control material. In these studies, urethane was used at a dose of 1,000 mg/kg/dose, administered intraperitoneally on days 1, 3, and 5. Urethane consistently produces lung adenomas and carcinomas and hemangiosarcomas of the spleen, proving validity of the assay. We conducted 3 pilot studies at 3 different sites of Charles River Laboratories using a lower dose of urethane (500 mg/kg/dose), administered on days 1, 3, and 5, followed by a 12-week observation period. Our results demonstrate that a lower dose can be used successfully with fewer number of animals per sex to prove the validity of the assay. However, based on our cumulative experience with this model, we propose to eliminate positive control dose groups in future Tg.rasH2 carcinogenicity studies.

gga-miR-26a targets NEK6 and suppresses Marek's disease lymphoma cell proliferation.

MicroRNA (miRNA) are a class of highly conserved, small noncoding RNA that emerge as key posttranscriptional regulators in various neoplastic transformations. Our previous study profiling the miRNA transcriptome in Marek's disease virus (MDV)-induced lymphoma revealed many novel and differentially expressed miRNA, including gga-miR-26a, which was downregulated in MDV-infected spleens of chickens. In this study, differential expression of gga-miR-26a between MDV-infected and noninfected spleens at 4, 7, 14, 21, and 28 d postinfection was analyzed by real-time PCR. The results showed gga-miR-26a were downregulated in MDV-infected spleens at cytolytic infection, latency, and tumor transformation phases. Subsequent cell proliferation assay revealed cell viability was lower in gga-miR-26a mimic transfection group than that in negative controls. Target genes of gga-miR-26a were identified by luciferase reporter gene assay. The results showed significant interaction between gga-miR-26a and Never In Mitosis Gene A (NIMA)-related kinase 6 (NEK6) gene. Subsequent gain of function experiment and Western blot assay showed that mRNA and protein levels of NEK6 were downregulated after gga-miR-26 mimic was transfected into MDV-transformed lymphoid cell line (MSB-1), indicating that NEK6 was modulated by gga-miR-26a. The expression of NEK6 showed a higher trend in MDV-infected samples including tumorous spleen and MD lymphoma from liver than that in noninfected controls. The results suggested that gga-miR-26a inhibited MSB-1 cell proliferation. Gga-miR-26a and its direct target, NEK6, might play important roles in MDV infection.

Extramedullary hemopoiesis and littoral cell angioma of the spleen: our experience and review.

Littoral cell angioma (LCA) is a rare primary vascular neoplasm of the spleen. A 54-year-old man was referred to our emergency department for abdominal pain. A CT scan showed multiple round hypodense lesions of various sizes throughout the spleen. The spleen was increased in volume. An MRI confirmed the lesion with a suspect of multiple angiomas vs. amartomas. The haematologists excluded any haematological disease. After a collegial discussion, we decided to perform laparotomic splenectomy. Histologically, the multiple lesions consisted in anastomosing vascular channels lined by plump cells. There was an increased number of dysmorphic megakaryocites inside the splenic parenchyma and along the tumour's border, known signs of extramedullary hemopoiesis, whose etiology in our patient was unexplained. To the best of our knowledge this is the third description of the association between littoral cell angioma and extramedullary hemopoiesis. LCA is a rare primary splenic vascular tumour that originates from the splenic littoral cells. The diagnosis of littoral cell angioma is confirmed histologically and on immunohistochemistry. This case report underlines the rarity of this type of benign splenic neoplams, but since the malignant potential of LCA, we recommend close clinical follow- up of patients with LCA of the spleen.

Splenic marginal zone lymphomas are characterized by loss of interstitial regions of chromosome 7q, 7q31.32 and 7q36.2 that include the protection of telomere 1 (POT1) and sonic hedgehog (SHH) genes.

To further characterize the genotypic features of splenic (S) and nodal (N) marginal zone lymphomas (MZL) we compared eight SMZL and five NMZL by array-based comparative genomic hybridization (aCGH). Arbitrarily, aberrations were divided into major imbalances, defined as gains or losses involving five or more contiguous genetic loci, and minor imbalances, defined as those involving four or fewer loci. SMZL, but not NMZL, demonstrated major imbalances. These included deletions involving various lengths of 7q (three cases), and 14q23q24 (one case) and gains of 9p13p21 (one case), 13q21q33 (one case) and 16p13.1 (one case). Common minor imbalances in SMZL were: loss of sonic hedgehog gene (SHH) at 7q36.2 (four cases), loss of protection of telomere 1 gene (POT1) at 7q31.32 (three cases), and gain of glioma associated oncogene 1 (GLI1) at 12q13.2 (three cases). Common minor alterations in NMZL were: loss of the fas-associated via death domain gene (FADD) at 11q13.2 (three cases) and gain of GLI1 (five cases). In conclusion, SMZL, but not NMZL, demonstrates large genomic imbalances and frequent loss of the 7q31.32 and 7q36.2 regions involving POT1 and SHH, respectively. In NMZL, loss of FADD and gain of GLI1 are frequent events.

Rare T-cell lymphomas.

The evolving classification systems in lymphoma have been driven by advances in the pathologic characterization of lymphoid malignancies. As evidenced by the detailed pathology descriptions earlier, subdividing heterogenous diseases results in an increasing number of distinct subtypes. This has allowed pathologists to provide more accurate diagnoses and begin to shed light on the molecular mechanisms that underlie these disorders. However, clinical information on these rare subtypes has lagged. Standard staging studies are less useful for these primarily extranodal diseases, although newer technologies such as PET scanning might be useful in detecting and following sites of disease. Optimal management remains undefined. Although these lymphomas are often aggressive, particularly in the case of ETCL, HSTCL, and GD-TCL, standard combination-chemotherapy regimens have only rarely provided durable remissions. Highdose therapy strategies have shown early promise, particularly for HSTCL, although conclusive data to support its routine use is lacking. Other strategies such as biologic therapies as with retinoids for SPTCL have provided durable benefit for some patients with less toxicity. Ultimately, it will take larger series with these rare but increasingly recognized entities to better define a preferred management approach.

[Inflammatory pseudotumor-like follicular dendritic cell tumor of spleen].

OBJECTIVE: To study the clinicopathologic features of inflammatory pseudotumor-like follicular dendritic cell tumor of spleen. METHODS: One case of inflammatory pseudotumor-like follicular dendritic cell tumor of spleen was examined macroscopically and microscopically. Immunohistochemical study for CD21, CD23, CD35, clusterin, S-100 protein, vimentin, smooth muscle actin, CD1a, CD68, ALK protein, CD30, CD31, CD34, CD3 and CD20 was performed on formalin-fixed, paraffin-embedded sections by standard EnVision method. In-situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was also carried out. RESULTS: Macroscopically, inflammatory pseudotumor-like follicular dendritic cell tumor was large in size, tan-colored, soft to rubbery in consistance and associated with central hemorrhage and necrosis. Histological examination showed scattered follicular dendritic cells admixed with abundant lymphocytes and plasma cells in the background, simulating inflammatory pseudotumor. On high-power magnification, the follicular dendritic cells possessed a moderate amount of pale to lightly eosinophilic cytoplasm, with indistinct cell borders. The nuclei were ovoid or spindly, with vesicular or stippled chromatin and small distinct, often centrally located, nucleoli. Some of the tumor cells showed nuclear pleomorphism and contained irregular foldings of nuclear membrane, coarse chromatin and prominent eosinophilic nucleoli. Mitotic figures were rarely identified. Immunohistochemical study showed that the tumor cells were positive for vimentin, clusterin, smooth muscle actin and CD68. They were weakly and focally positive for CD35 and S-100 protein, but negative for CD21, CD23, CD1a, ALK protein, CD30, CD31 and CD34. Most of the background lymphocytes were of T-lineage (CD3-positive) ,some were CD20 (B-cell marker)-positive. EBV RNA was demonstrated in the tumor cells by in-situ hybridization analysis. CONCLUSIONS: Inflammatory pseudotumor-like follicular dendritic cell tumor is a rarely encountered low-grade malignancy with distinctive morphologic pattern. It is associated with EBV infection.

Splenic tumor presenting as pyrexia of unknown origin.

Pyrexia of unknown origin has always been a challenging problem to diagnose for physicians. Here we present a case of a splenic tumor, which after histopathology and immunohistochemistry, two possibilities were considered, a diffuse large cell lymphoma--plasmablastic variant and second an anaplastic plasmacytoma. The patient was treated with chemotherapy and on followup he has no evidence of recurrence or any residual lesion.

Protective mechanisms of purified polyphenols from pinecones of Pinus koraiensis on spleen tissues in tumor-bearing S180 mice in vivo.

The previous study evaluated the antitumor activity and the underlying mechanism of the purified polyphenols from pinecones of Pinus koraiensis (PPP-40) using a tumor-bearing S180 mice model. This study was designed to evaluate the protective effects of PPP-40 on spleen tissues of S180 mice in vivo. Pretreatment with PPP-40 (150 mg per kg BW per D) could significantly inhibit tumor growth, enhance spleen index and prevent the decline of haematological parameters of S180 mice induced by the tumor microenvironment. Moreover, the treatment with PPP-40 was shown to significantly inhibit splenocyte apoptosis by TUNEL staining and flow cytometry, characterized by the inhibition of splenocyte cycle (G0/G1) arrest, increase in the percentages of splenic T lymphocytes (CD3+ T cells) and T cell subsets (CD3+CD4+ and CD3+CD8+ T cells), as well as the production of T cell-related cytokines (IL-2, IL-12, and TNF-α) in splenocytes exposed to the tumor microenvironment. These effects were associated with a decrease in oxidative stress, as evidenced by the changes in the SOD, GSH-Px, GSH and MDA levels of liver and spleen tissues of S180 mice. Furthermore, the protective effect of PPP-40 on spleen tissues was deeply analyzed by detecting apoptosis-related proteins using immunohistochemistry staining. The results indicated that the protective multi-mechanisms of action also were associated with the inhibition of apoptosis through down-regulation protein expressions of Bax, caspase-9, caspase-8 caspase-3, Fas and up-regulation of the expressions of Bcl-2. These results suggested that PPP-40 is a natural antitumor agent and possesses strong immunomodulatory activities by protecting the spleen tissues of tumor-bearing S180 mice.

Dynamics of the spleen and its significance in a murine H22 orthotopic hepatoma model.

The dynamics of the spleen during tumor progression remains incompletely understood. In this study, we established a murine H22 orthotopic hepatoma model and dynamically detected alterations in the percentages of immunocytes in the spleen. We observed a prominent myeloid-derived suppressor cell (MDSC) accumulation during the early response which persisted through all the stages of tumor growth. In addition, the percentage of regulatory T cells (Tregs) increased by week 2. Although the percentage of CD3(+)CD49b(+) natural killer T (NKT) cells increased by day 3, and that of CD3(+)CD4(+) T cells slightly increased by week 1, they decreased to either normal or lower levels compared with those of normal mice. The percentages of total CD3(+), CD3(+)CD4(+), and CD3(+)CD8(+) T cells decreased by week 2, and that of NK cells decreased by week 3. The activation of non-Treg CD4(+) T cells was scarce. Moreover, splenic MDSCs of tumor-bearing mice suppressed the activation of splenocytes. Therefore, a negative immune response gradually prevailed over a positive immune response during tumor growth. In addition, splenectomy was performed at the time of tumor inoculation, and we found that splenectomy could prolong the survival time, reduce the tumor weights, decrease the ascites volumes, and ameliorate the immune status of the tumor-bearing mice. Splenectomy also decreased the percentage of MDSCs and increased the percentages of CD8(+) T cells, NK, and NKT cells in tumor tissues. Additionally, splenectomy decreased the percentage of MDSCs and increased that of CD8(+) T cells in peripheral blood. Overall, our findings suggest that immune-negative cells are dominant in the spleen during tumor progression. Splenectomy could be helpful to improve the immune responses of tumor-bearing hosts.

Cytoplasmic components of natural killer cells limit the growth of Cryptococcus neoformans.

Murine natural killer (NK) cell-mediated inhibition of growth of a yeast-like target cell, Cryptococcus neoformans, was completely abrogated by blocking the effector cell secretory process with monensin. Therefore, further studies were performed to determine the ability of various cytoplasmic fractions of NK cells to mediate inhibition of cryptococcal growth. Percoll-fractionated homogenates of rat LGL tumor cells demonstrated that the granule-containing fractions plus three additional sets of less dense cytoplasmic fractions displayed anti-cryptococcal activity; whereas only the cytoplasmic granule-containing fractions had cytotoxic activity against YAC-1 tumor cell and sheep erythrocyte targets. Maximal cryptococcal growth inhibition induced by LGL granules occurred after a 1 h incubation, required the presence of Ca2+ (1.0 mM) or Mg2+ (0.5 mM or 5.0 mM), and was completely abrogated in the presence of rabbit anti-LGL granule IgG. Cytolysin, the granule component which mediates tumor cell and sheep erythrocyte lysis, effectively limited the growth of cryptococci. Since Percoll gradient fractionation of the LGL homogenates demonstrated three separate peaks of anti-cryptococcal activity other than the granule peak, it is possible that the cytolysin-containing granules are not the only subcellular component of NK cells playing a role in inhibition of C. neoformans growth.

Spleen and retroperitoneum: the essentials.

This is a survey of normal variants and pathologic conditions involving the spleen and retroperitoneum. The study focuses on the various sonographic appearances of trauma, infection, and neoplasm involving these areas in an attempt to complement works dealing specifically with the pancreas, kidneys, and great vessels. Ultrasound-guided intervention (biopsy, drainage) is included.

Splenic lymphoma with circulating villous lymphocytes/splenic marginal-zone lymphoma.

Splenic lymphoma with villous lymphocytes (SLVL) represents a low-grade B-cell non-Hodgkin's lymphoma (NHL) that histologically is indistinguishable from splenic marginal-zone lymphoma (SMZL). Characteristic features of SLVL are splenomegaly, moderate lymphocytosis, nodular and intrasinusoidal pattern of bone marrow infiltration, serum monoclonal band, slow benign course, and response to splenectomy. The diagnosis is made by the morphology of the circulating villous cells and their immunophenotype, which is distinct from that of chronic lymphocytic leukemia (CLL) and hairy-cell leukemia (HCL), diseases with which SLVL may be confused. When treatment is indicated, splenectomy is the treatment of choice, but some patients may require additional chemotherapy to control progression. In those circumstances, fludarabine may be the agent of choice. Despite its unique features, which, compounded, suggest that SLVL is a clinicopathologic entity, there are no specific chromosome abnormalities and problems of differential diagnosis with other B-cell NHLs, chiefly mantle-cell lymphoma (MCL), remain in a minority of patients.

Human and murine Kupffer cell function may be altered by both intrahepatic and intrasplenic tumor deposits.

The liver is the most common site of hematogenous metastases from colorectal carcinoma. Kupffer cells (KC), which line the hepatic sinusoids, may form the first line of defense against circulating tumor cells. The purpose of this study was to determine the effect of hepatic metastases and intra-abdominal tumor growth on KC binding of human colorectal carcinoma (HCRC) cells. MIP-101, a poorly metastatic cell line, and CX-1, a highly metastatic cell line, were injected intrasplenically into nude mice and KC were isolated by collagenase perfusion at varying intervals after injection. Conditioned media were collected from MIP-101, CCL 188 and CX-1 to determine their in vitro effect on KC function. KC from MIP-101 injected mice (14% liver metastases, 100% splenic tumors) bound a significantly greater number of MIP-101 and clone A cells than CX-1 cells in vitro. KC isolated from mice 5 weeks after CX-1 injection (100% liver metastases) also showed increased binding of MIP-101 and clone A cells compared to CX-1 cells. Similar results were obtained when tumor cell binding to normal human liver KC was compared to binding to KC from human livers from patients with hepatic metastasis from colorectal cancer. In contrast KC obtained from mice 3 weeks after CX-1 injection (44% liver metastases) showed significantly decreased binding of MIP-101 and clone A cells. The conditioned medium from CX-1 cells significantly decreased the in vitro binding of both MIP-101 and CX-1 by KC. These results indicate that the ability of KC to bind HCRC cells (which precedes phagocytosis and tumor cell killing) is a dynamic function and affected by concomitant tumor growth. HCRC cells may alter KC function via the production of specific tumor-derived soluble factors. In order to devise new and more effective therapeutic options in the treatment of liver metastases the nature of this tumor cell-KC interaction must be better understood.

Primary angiosarcoma of the spleen. A clinicopathologic study of 40 cases.

Forty primary splenic angiosarcomas occurring in 21 men and 19 women, 19-84 years old (median 59 years) are reported. Patients presented with splenomegaly (35 of 38, 92%), abdominal pain (33 of 40, 83%), and systemic symptoms such as fatigue (2 of 40, 5%), fever (4 of 40, 10%), and/or weight loss (16 of 40, 40%). Five (13%) experienced splenic rupture associated with hemoperitoneum. Abnormal laboratory findings included cytopenia (31 of 34, 91%), leukocytosis (8 of 21, 38%), and thrombocytosis (1/39, 3%). Most spleens weighed 500-1,000 g (mean, 1,180 g). The cut splenic surfaces showed multiple hemorrhagic nodules that were frequently associated with infarction, although some had a diffuse pattern of involvement. Microscopically, there were a variety of histologic patterns displayed by the vasoformative component. A honeycomb or sponge-like pattern was common in some, whereas others simulated a cavernous hemangioma or normal splenic sinuses (pseudosinusoidal pattern). Papillary endothelial tufts and solid proliferations of spindled to round to epithelioid cells were also seen. Factor VIII-related antigen was detected in 19 of 23 cases, BMA-120 in 18 of 23, UEA-1 receptor in 18 of 23, and vimentin in 23 of 23 as well as CD68 antigen in 1 of 23 cases. S-100 protein and cytokeratin were not found in any of the 23 cases studied. Metastases in 22 of 32 patients (69%) were to the liver (13 patients), bone or bone marrow (7 patients), lymph nodes (1 patient), and brain (1 patient). Three patients had concomitant malignancies and one had a prior history of a mixed B-cell lymphoma 5 years previously that had been treated with chemotherapy. Follow-up in 38 patients revealed that 30 (79%) are dead at a median interval of 6 months (range 0-48 months) and 8 are alive 5-21 months after diagnosis. These findings indicate that splenic angiosarcoma is an aggressive neoplasm with a high metastatic rate and an abysmal prognosis. Recognition of the wide range of histologic patterns is of diagnostic value but no apparent prognostic significance.

Functional hyposplenism due to a primary epithelioid hemangioendothelioma of the spleen.

We present a unique case of functional hyposplenism due to massive involvement of the spleen by a rare tumor, an epithelioid hemangioendothelioma, in a 9-year-old girl. To our knowledge, three previous cases of this disorder involving the spleen have been reported, but this is the first associated with functional hyposplenism.

Aniline: early indicators of toxicity in male rats and their relevance to spleen carcinogenicity.

Early indicators of aniline hydrochloride (AH) toxicity were investigated in male Fisher 344 rats for 1 or 4 weeks at dietary dose levels of 10, 30 or 100 mg/kg body weight (bw)/day (actual intake at least 6, 17 and 57 mg/kg). The doses were based on earlier studies that had shown spleen toxicity and carcinogenicity in male rats at 100 mg/kg/day but not at 10 mg/kg/day. In the present study a dose-related formation of haemoglobin adducts and Heinz bodies was found from 10 and 30 mg/kg bw/ day, respectively, onwards. Signs of anaemia (decreased red blood cell counts and increased reticulocytes) were recorded from 30 mg/kg onwards. At 100 mg/kg, an overt haemolytic anaemia was associated with increases in serum transferrin concentration and total iron binding capacity in the blood reflecting major perturbations in iron metabolism. At this dose there was an increase in peripheral neutrophil leucocytosis in the blood, indicating an inflammatory process in the spleen. Histopathologic evaluation showed a focal perisplenitis and haemosiderin deposition in sinusoidal Kupffer cells of the liver at 100 mg/kg. These results corroborate the contention that carcinogenic doses of aniline cause early effects on haematological parameters, inflammatory reaction in the spleen and perturbations in iron metabolism as a result of haemolytic anaemia. Accordingly, the carcinogenicity of aniline may be linked to definable threshold-related processes.

Epitheloid angiosarcoma of the splenic capsula as a result of foreign body tumorigenesis. A case report.

A case of an epitheloid angiosarcoma of the splenic capsula is reported. This tumour developed in close relation to a gauze sponge, which was accidentally left behind 38 years earlier during a left-sided nephrectomy. The tumour probably arose from pluripotential mesothelial stem cells within the splenic capsula, with subsequent mesothelial to endothelial metaplasia and neoplastic transformation. Clinical, radiological, peroperative and pathological features of this angiosarcoma add to the validity of the concept of inert foreign body tumorigenesis.